Method for manufacturing a bearing shell assembly and bearing shell assembly for a ball joint

ABSTRACT

A method for manufacturing a bearing shell assembly for a ball joint includes the following steps: a) a bearing shell having a plastic extension is produced; b) a spring element is arranged in a region of the plastic extension; and c) the spring element is fastened to the bearing shell by deformation of the plastic extension. The invention further relates to a bearing shell assembly for a ball joint, including a bearing shell and a spring element, the spring element being non-detachably connected with the bearing shell.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. Ser. No. 12/348,921, filed Jan.6, 2009, which claimed priority to German Patent Application No. 10 2008003 463.0 filed Jan. 8, 2008, the disclosures of which are incorporatedherein by reference in their entirety.

BACKGROUND OF THE INVENTION

The invention relates to a bearing shell assembly for a ball joint and amethod for manufacturing a bearing shell assembly.

Ball joints are generally known from the prior art and are employed,inter alia, in vehicle construction. For example, they are used asradial ball joints and, in that case, must be able to withstand highradial forces along with low axial forces and large tilting angles. Thewear occurring over the lifespan of a radial ball joint can lead to theball joint causing noises during travel, caused by free play in thejoint.

In order to prevent the occurrence of this free play, ball jointsalready exist in which a pre-stressed spring element is arranged betweena joint housing and a bearing shell in the composed state of the joint.Through the pre-stressing of the spring element, the bearing shell isacted upon against the ball head of the ball pin, so that even if wearoccurs to the bearing shell, a permanent contact exists between thebearing shell and the ball pin, and no free play occurs between the ballhead and the bearing shell.

In addition, it is known to provide an extension on the bearing shell,on which the spring element can be pre-mounted. On the one hand, thisfacilitates a simple and exact positioning of the spring element in thejoint housing and, on the other hand, simplifies the assembly of theball joint.

In the prior art, for example a bearing shell is disclosed (cf. FIG. 1),in which the extension is constructed as a latching element, in order toenter into a snap-on connection with the spring element (not shown).However, specifically in the case of a preferred production of thebearing shell as an integral injection molded plastic part, theconstruction of the extension as a latching element involvesconsiderable effort. In particular, the provision of notches for theformation of radially movable detent arms and also the forming of anundercut on the detent arms for the formation of radial detent noses atthe free end of the extension is complex with regard toinjection-molding technique.

It is a feature of the invention to produce a favorably priced,pre-mounted assembly of a bearing shell and a spring element with aslittle effort as possible.

BRIEF SUMMARY OF THE INVENTION

According to the invention, this feature is achieved by a method formanufacturing a bearing shell assembly for a ball joint, the methodincluding the following steps:

-   -   a) a bearing shell having a plastic extension is produced;    -   b) a spring element is arranged in a region of the plastic        extension; and    -   c) the spring element is fastened to the bearing shell by        deformation of the plastic extension.

The connection between the spring element and the bearing shelltherefore takes place by a simple deformation of the plastic extension,which can be carried out mechanically with little effort. In return,with regard to injection-molding technique, the complex manufacture ofalternative connecting means, such as latching elements for example, isdispensed with.

In a method variant, the bearing shell and the plastic extension areproduced as an integral injection-molded part. This integral embodimentpermits a particularly favorably priced production of the bearing shell,in particular owing to the fashioning of the plastic extension which issimplified with regard to injection-molding technique.

In step a) the plastic extension is preferably produced as asubstantially hollow cylindrical extension having a free axial end. Thistechnical design of the extension makes possible a particularly simpleand reliable mechanical deformation at the free axial end.

In a preferred method variant, the spring element is fastened to thebearing shell by cold deformation of the plastic extension. “Colddeformation” in this context designates a deformation which takes placeapproximately at room temperature, so that a special heating of theplastic extension before deformation is superfluous. This contributes toa production of the bearing shell assembly which is energetic favorableand hence is particularly favorably priced.

The spring element may have an opening for the plastic extension and maybe placed onto the bearing shell in step b), such that the springelement surrounds the plastic extension. In this case, a particularlysimple and reliable positioning of the spring element on the bearingshell is achieved.

Preferably, with the deformation in step c), an external diameter of thesubstantially hollow cylindrical plastic extension is widened. A springelement being formed in a suitable manner can be fastened captively, inparticular non-releasably, on the bearing shell owing to this wideningof the external diameter.

In particular, the spring element may be a plate spring or an assemblyof several plate springs.

The invention further relates to a bearing shell assembly for a balljoint, which is preferably produced by the previously described method,with a bearing shell and a spring element, the spring element beingnon-releasably connected to the bearing shell.

Other advantages of this invention will become apparent to those skilledin the art from the following detailed description of the preferredembodiments, when read in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the perspective view of a bearing shell according to theprior art;

FIG. 2 shows the perspective view of a bearing shell for a bearing shellassembly according to the invention;

FIG. 3 shows a diagrammatic section through the bearing shell accordingto FIG. 2 with a spring element fitted in place, the bearing shell beingclamped into a deformation tool;

FIG. 4 shows a perspective view of the bearing shell according to FIG. 2with a spring element fitted in place, the bearing shell being clampedinto a deformation tool;

FIG. 5 shows a perspective view of a bearing shell assembly according tothe invention;

FIG. 6 shows a longitudinal section through a ball joint with a bearingshell assembly according to the invention; and

FIG. 7 shows a detail section through the ball joint according to FIG. 6in the region of a plastic extension of the bearing shell assemblyaccording to the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a known bearing shell 10′ for a ball joint, with a shapewhich is substantially rotationally symmetrical to a longitudinal axisA′. The bearing shell 10′ has an axial extension 12′, on which latchingelements 14′ are formed. The latching elements 14′ can enter into asnap-on connection with a spring element (not shown) in order to fastenthe spring element to the bearing shell 10′, so that a pre-mountedbearing shell assembly is produced. According to FIG. 1, the axialextension 12′ is subdivided by notches 16′ into four radially movablelatching elements 14′. At a free, axial end 18′ of the extension 12′,each latching element 14′ has a formed-on build-up or undercut, whichrespectively forms a detent nose 20′ of the associated latching element14′.

If a spring element, such as for example a plate spring with a suitableopening, is pressed in the axial direction onto the extension 12′, thenthe latching elements 14′ deform radially inwards until the plate springhas passed the detent noses 20′. Thereafter, the elastic latchingelements 14′ snap radially outwards again, so that the detent noses 20′engage behind an edge of the opening of the plate spring and thereforefasten the plate spring to the bearing shell 10′. Depending on theconstruction of the latching elements 14′, the plate spring can bedetached again from the extension 12′ by a suitable tool or an axialforce, without the bearing shell 10′ being damaged or destroyed.

According to FIG. 1, the bearing shell 10′ and the extension 12′ areproduced integrally as a single plastic part, in which the forming-on ofthe notches 16′ and the detent noses 20′ involves considerable effortwith regard to injection-molding technology.

FIG. 2 shows a bearing shell 10 which is likewise substantiallyrotationally symmetrical to a longitudinal axis A, but has an alteredaxial plastic extension 12, in which this plastic extension 12, comparedwith the extension 12′ according to FIG. 1, is able to be produced in asubstantially simpler manner with regard to injection-molding technique.Preferably, the bearing shell 10 and the plastic extension 12 accordingto FIG. 2 are also produced in a single process step as an integral,favorably priced injection-molded part. The plastic extension 12 ispreferably formed as a substantially hollow cylindrical extension havinga free axial end 18. In some variant embodiments, an outer side of theextension 12 is not exactly cylindrical, but rather is constructed so asto be slightly conical, such that the extension 20 narrows slightlytowards the free end 18. This conical embodiment facilitates theplacement of a spring element 22 (cf. FIGS. 3 to 7) and, moreover,simplifies the material deformation in this region owing to the smallerwall thickness at the free end 18 of the extension 12.

The bearing shell 10 according to FIG. 2 constitutes a suitable blankfor the production of a bearing shell assembly 23 according to FIG. 5,with the production process of this bearing shell assembly 23 beingdescribed in detail below with the aid of FIGS. 3 and 4.

After a manufacture of the bearing shell 10 shown in FIG. 2 in a firstprocess step, the spring element 22 is arranged in the region of theplastic extension 12 in a second process step. Preferably, a platespring or a plate spring set is used as spring element 22. Basicallyhowever, any desired spring element 22 can be used which acts upon thebearing shell 10 in the desired manner when subsequently employed in aball joint 34 (cf. FIGS. 6 and 7).

In the present example, the spring element 22 includes two plate springswith respectively a central, approximately circular opening 24, adiameter of the opening 24 being slightly larger than an externaldiameter d₁ of the substantially hollow cylindrical plastic extension 12(cf. FIGS. 2 and 3). Accordingly, the spring element 22 can be placedonto the plastic extension 12 and is thereby already largely fixed in aradial direction.

In a further, third process step, the spring element 22 is fastened onthe bearing shell 10 by deforming the plastic extension 12. This processstep is illustrated diagrammatically in FIG. 3. In actual terms, firstlythe bearing shell 10 on its side facing away from the extension 12 isturned over a form 26 which serves as an abutment. Then a pressure stamp28 is supplied in the axial direction, the pressure stamp 28 engaging atthe free end 18 of the plastic extension 12. The shape of the pressurestamp 28 in the contact region with the plastic extension 12 isillustrated precisely on the left-hand side of FIG. 3 by means of asection detail X. A stamp extension 30, which narrows conically towardsa free end of the pressure stamp 28, engages into the hollow cylindricalplastic extension 12 of the bearing shell 10 and widens the extensionslightly by applying axial pressure. Finally, the free end 18 of theextension 12 abuts onto a rounded, encircling guide channel 32 of thepressure stamp 28, which deforms the plastic material at the free end 18of the extension 12 radially outwards such that an encircling build-up33 is formed. In other words, the external diameter of the substantiallyhollow cylindrical plastic extension 12 is widened during thedeformation by the pressure stamp 28. In the present example, theexternal diameter is increased in the region of the free end 18 from avalue d₁ to a value d₂ (cf. FIGS. 2 and 6).

With the deformation of the plastic extension 12 in this third processstep, it is particularly important that the longitudinal axes of theform 26, the pressure stamp 28 and the bearing shell 10 are precisely inalignment, so that a uniform deformation takes place, viewed in aperipheral direction.

FIG. 4 shows a perspective view during the process which is illustratedaccording to FIG. 3 in a diagrammatic longitudinal section. Here, thebearing shell 10 is turned over the form 26 and the spring element 22 isplaced onto the extension 12 of the bearing shell 10. Furthermore, thepressure stamp 28 is already placed onto the free end 18 of theextension 12 and is acted upon against the form 26. After thedeformation of the free end 18, the pressure stamp 28 moves away againin the axial direction and the bearing shell assembly 23 can be takenfrom the form 26. Through the deformation of the free end 18, the springelement 22 is now fastened both in radial and axial direction on thebearing shell 10. In addition to the spring element 22, of coursefurther components such as for example a washer 35 (cf. FIG. 6) can alsobe fastened on the bearing shell 10 by the described method.

Depending on the boundary conditions during the manufacturing process,in the finished bearing shell assembly 23 the spring element 22 ispossibly rotatable relative to the bearing shell 10 about the axis Aand/or has a slight axial play. However, as the objective was the (inparticular radial) positioning of the spring element 22 relative to thebearing shell 10 and the non-releasable fastening of the spring element22 on the bearing shell 10, these movement possibilities in no wayrestrict the operability of the bearing shell assembly 23 and aretherefore negligible.

FIG. 5 shows a perspective view of the pre-mounted bearing shellassembly 23, which has been manufactured by the method described above.The bearing shell assembly 23 includes the bearing shell 10 and thespring element 22, the spring element 22 being non-releasably connectedwith the bearing shell 10. In this case, the connection is defined asbeing non-releasable because the spring element 22 can not be detachedfrom the bearing shell 10 without destroying or at least damaging theextension 12.

To produce at least the extension 12, preferably the entire bearingshell 10, plastics (in particular thermoplastics) are used, which aresuitable for a permanent plastic deformation. In a variant embodiment,the deformation takes place at raised temperatures, which is designatedas so-called hot deformation. However, in particularly preferred variantembodiments, the spring element 22 is fastened to the bearing shell 10by so-called cold deformation, i.e. cold overstretching of the plasticextension 12. During cold deformation, the plastic material is deformedbeyond the linear-elastic range, up to close to the yield point. Thedeformation in this so-called entropy-elastic or plastic range ismaintained substantially permanently, so that the spring element 22 isreliably fastened on the bearing shell 10.

FIG. 6 shows a ball joint 34 with a ball pin 36, a joint housing 38 andthe bearing shell assembly 23 described above. In the present case, thejoint housing 38 includes a housing cover 40 and a peripheral wall 42 onwhich the housing cover 40 is fastened. The bearing shell assembly 23 isaccommodated inside the joint housing 38 and surrounds a ball head 44 ofthe ball pin 36, which likewise extends into the interior of thehousing. In this assembled state of the ball joint 34, it becomes clearthat the spring element 22 can be pre-stressed by the placement of thehousing cover 40. Through the pre-stressing of the spring element 22,the bearing shell 10 is pressed against the ball head 44 of the ball pin36, so that even when wear occurs to the bearing shell 10, a permanentcontact exists between the bearing shell 10 and the ball pin 36 and nofree play occurs between the ball head 44 and the bearing shell 10.

FIG. 7 shows a detail of the ball joint 34 according to FIG. 8 in theregion of the axial plastic extension 12. The widened externalcross-section d₂ at the free end 18 of the plastic extension 12, whichprovides for a captive, in particular non-releasable connection betweenthe bearing shell 10 and the spring element 22 can be readily seen here.

In accordance with the provisions of the patent statutes, the principleand mode of operation of this invention have been explained andillustrated in its preferred embodiments. However, it must be understoodthat this invention may be practiced otherwise than as specificallyexplained and illustrated without departing from its spirit or scope.

What is claimed is:
 1. A ball joint comprising: a ball joint housing; abearing shell disposed in the housing and having a plastic extension;and a spring element arranged in a region of the plastic extension,wherein an outer circumference of the spring element is free andradially spaced from the ball joint housing, wherein the spring elementincludes an opening for receiving the plastic extension, wherein theopening defines a continuous and non-deformable inner diameter, whereinthe spring element is a plate spring or an assembly of several platesprings; wherein a free axial end of the plastic extension, which is notwithin the region of the spring element includes a continuouslyencircling non-deformable build-up which defines a first externaldiameter, and the plastic extension, which is directly adjacent the freeaxial end and within the region of the spring element defines a secondexternal diameter which is less than the first external diameter tothereby non-releasably fasten the spring element to the bearing shellonly in the region of the plastic extension of the bearing shell whichis directly adjacent the free axial end thereof.
 2. The ball joint ofclaim 1, wherein the bearing shell and the plastic extension areproduced as an integral injection-molded part.
 3. The ball joint ofclaim 1, wherein the plastic extension is a substantially hollowextension.
 4. The ball joint of claim 1, wherein the continuouslyencircling build-up of the free axial end is formed during a deformationprocess and prior to the deformation process an outer side of the freeaxial end is conical.
 5. The ball joint of claim 1, wherein thecontinuously encircling build-up of the free axial end is formed duringa deformation process.
 6. The ball joint of claim 1, wherein the springelement is fastened to the bearing shell by one of a hot deformation ora cold deformation of the plastic extension.
 7. The ball joint of claim1, wherein the inner diameter of the opening of the spring element isslightly larger than the second external diameter of the plasticextension of the bearing shell.
 8. A ball joint comprising: a ball jointhousing; an injection-molded bearing shell disposed in the housing andhaving an integral substantially hollow plastic extension having a freeaxial end; and a spring element arranged in a region of the plasticextension, wherein an outer circumference of the spring element is freeand radially spaced from the ball joint housing, wherein the springelement includes an opening for receiving the plastic extension, whereinthe opening defines a continuous and non-deformable inner diameter,wherein the spring element is a plate spring or an assembly of severalplate springs; wherein the free axial end of the plastic extension,which is not within the region of the spring element includes acontinuously encircling non-deformable build-up which defines a firstexternal diameter, and the plastic extension, which is directly adjacentthe free axial end and within the region of the spring element defines asecond external diameter which is less than the first external diameterto thereby non-releasably fasten the spring element to the bearing shellonly in the region of the plastic extension of the bearing shell whichis directly adjacent the free axial end thereof.
 9. The ball joint ofclaim 8, wherein the continuously encircling build-up of the free axialend is formed during a deformation process and prior to the deformationprocess an outer side of the free axial end is conical.
 10. The balljoint of claim 8, wherein the spring element is fastened to the bearingshell by one of a hot deformation or a cold deformation of the plasticextension.
 11. The ball joint of claim 8, wherein the inner diameter ofthe opening of the spring element is slightly larger than the secondexternal diameter of the plastic extension of the bearing shell.
 12. Aball joint comprising: a ball joint housing; an injection-molded bearingshell disposed in the housing and having an integral substantiallyhollow plastic extension; and a spring element arranged in a region ofthe plastic extension, wherein an outer circumference of the springelement is free and radially spaced from the ball joint housing, whereinthe spring element includes an opening for receiving the plasticextension, wherein the opening defines a continuous and non-deformableinner diameter, wherein the spring element is a plate spring or anassembly of several plate springs; wherein a free axial end of theplastic extension, which is not within the region of the spring elementincludes a continuously encircling build-up which defines a firstexternal diameter, the build-up formed by one of a hot deformation or acold deformation process, and the plastic extension, which is directlyadjacent the free axial end and within the region of the spring elementdefines a second external diameter which is less than the first externaldiameter to thereby non-releasably fasten the spring element to thebearing shell only in the region of the plastic extension of the bearingshell which is directly adjacent the free axial end thereof.
 13. Theball joint of claim 12, wherein the plastic extension has asubstantially hollow extension.
 14. The ball joint of claim 13, whereinprior to the forming of the continuously encircling build-up of the freeaxial end by the one of the hot deformation or the cold deformationprocess, an outer side of the free axial end is conical.
 15. The balljoint of Claim 12, wherein the inner diameter of the opening of thespring element is slightly larger than the second external diameter ofthe plastic extension of the bearing shell.
 16. A ball joint comprising:a ball joint housing; a bearing shell disposed in the housing and havinga plastic extension; a spring element arranged non-releasably in aregion of the plastic extension, wherein an outer circumference of thespring element is free and radially spaced from the ball joint housing,wherein the spring element includes an opening for receiving the plasticextension, wherein the opening defines a continuous and non-deformableinner diameter; and a housing cover fastened to the ball joint housing;wherein the spring element is prestressed between the housing cover andthe bearing shell; and wherein a free axial end of the plasticextension, which is not within the region of the spring element includesa continuously encircling non-deformable build-up which defines a firstexternal diameter, and the plastic extension, which is directly adjacentthe free axial end and within the region of the spring element defines asecond external diameter which is less than the first external diameterto thereby non-releasably fasten the spring element to the bearing shellonly in the region of the plastic extension of the bearing shell whichis directly adjacent the free axial end thereof.
 17. The ball joint ofclaim 16 wherein the plastic extension is substantially hollow.
 18. Theball joint of claim 17 wherein the continuously encircling build-up ofthe free axial end is formed during a deformation process and prior tothe deformation process an outer side of the free axial end is conical.